1. Field of the Invention
The present invention relates to hematology analyzers and to analyzers of the fully automated type which require little or no operational "hands on" activity by attendant operators.
More particularly, the invention has to do with automatic means and method for monitoring human blood samples and detecting the presence of contaminants therein, such as air bubbles, etc.
2. Description of the Prior Art
A wide variety of mechanisms and apparatuses have been suggested and patented for detecting contaminants in fluid flow, such as air bubbles in blood flow hematology apparatuses.
U.S. Pat. No. 4,280,495, entitled "Air Emboli Detection", describes and claims a method and apparatus for use in cardiopulmonary bypass surgery wherein a modular sensor is adapted to releasably clamp a blood flow tubing in a vertical orientation below, and includes an LED infrared source and a photodetector. Pulsed power is applied to the light source only at preselected periodic intervals for removing power to a blood pump when emboli are detected.
This construction is quite dissimilar to that of the present application.
U.S. Pat. No. 4,312,341, entitled "Bubble Detector", describes a flow metering apparatus for detecting bubble formation in tubing subject to deformation from internal fluid pressure, wherein a light detector is positioned on the opposite side of the tubing from a light source, such that light transmitted through the tubing to the detector is dependent on the presence of fluid in the tubing and the shape of the lumen of the tubing. Control means interrupts the fluid flow when received light falls below a predetermined level. Tubing deformation due to pressure changes in the fluid are prevented by forming members surrounding the tubing.
The described arrangement differs quite measurably from Applicant's claimed combination.
In U.S. Pat. No. 4,344,429, entitled "Bubble Detector with Feedback Circuit for Improved Sensitivity", there is described and illustrated a flow metering apparatus for use with transparent tubing utilizing the lens effect of fluid within the lumen of the tubing to detect the presence of fluid within the tubing. A single light source is positioned on one side of the tubing and two angularly displaced light detectors are placed on the opposite side of the tubing. The variation in intensity of the detected light due to the presence of or absence of fluid is an indication of a bubble in the system.
Applicant's structural combination is completely different than this arrangement.
U.S. Pat. No. 4,371,786, entitled "Method and Apparatus for Detecting Bubbles in a Liquid" relates to: A method and apparatus for sensing the presence of bubbles in a liquid wherein radiation is directed through said liquid toward a radiation responsive sensor and the differential between the response of the sensor when a bubble is not present in the radiation path and the response thereof when a bubble is present in the radiation path is markedly increased by limitation of the radiation which can reach said sensor to wavelengths strongly absorbed by said liquid.
As with the preceding patented apparatus, Applicant's bubble detection mechanism and method are quite different from the foregoing.
The "Air Bubble Detector" of U.S. Pat. No. 4,366,384 describes an apparatus in which multiple pairs of light sensors are positioned along a transparent pipe, such that light is directed to one sensor of each pair while light is reflected to the other sensor of each pair. The reflective sensor of each pair is positioned midway between a light source and its associated direct light receiving sensor. The outputs of the two light sensors are fed into a logic circuit, which produces one output when the light levels seen by the two sensors are generally alike, and another output when they are substantially different. If a bubble is present, both sensors see a high light level.
The dual sensor bubble detector apparatus of the present application is markedly different from the apparatus hereinabove described, both in function and construction.
"Contaminant Detector Comprising Means for Selectively Applying Pressure to Liquify Bubbles", as described in U.S. Pat. No. 3,680,962, relates to an apparatus in which a rigid metal tube open at opposite ends is provided with an angularly disposed branch tube integral therewith. A light source is disposed at one end of the tube and a first photo-optical sensor is placed at its opposite end. A second photo-optical sensor is positioned at the open end of the branch tube, with liquid contained in the tube having contaminants therein. Light is scattered and absorbed by the contaminants, so that a reduced amount of light is received by the first sensor as compared with a contaminant free liquid, which provides a greater resistance value at the first sensor. In contrast, the light scattered by the contaminants in the branch tube decreases the second sensor's resistance value. By means of an operably coupled bridge circuit, the variation in resistance values of the first and second sensors can be converted into a variation of light intensity, so as to detect contamination or a clear tube.
This is completely dissimilar to Applicant's method and apparatus as set forth in the Specification hereinafter.
A U.S. Pat. No. 4,418,565, entitled "Ultrasonic Bubble Detector", describes a rigid housing of glass-filled polytetrafluoroethylene having a channel in this one-piece housing for receiving flow tubing in which bubbles are detected. A first ultrasonic sending transducer means is positioned in the housing on one side of the channel. A second ultrasonic receiving transducer means is positioned on the other side of the channel, the sending and receiving transducer means being of the type for respectively sending and receiving ultrasound energy at a frequency of 1 to 3 megahertz. The presence of a bubble significantly alters the transmission of ultrasound energy. This alteration is electronically detected.
This construction is in complete contrast to the simplified bubble sensor arrangement of Applicant's application.